EDIT: the fix for this issue was merged in the master QtCreator branch, but it was not included in the latest release (4.5.0) yet.
If someone with non-english system locale has issues with QtCreator, he can use the bleeding-edge QtCreator.

Does anyone use the QtCreator on Linux for OpenMW development?
QtCreator 4.5.0 in my setup for some reason fails to detect non-OpenMW headers.
Also only editor is affected: I can successfully build and run OpenMW.

Note: There was a related bug in the QtCreator, but devs claimed it fixed.
How can I setup QtCreator to use it for OpenMW development?